The present invention relates generally to firearms, and more particularly to a hammer release assembly for a hand-held weapon which allows for a reduced trigger-pull.
Various hammer release assemblies are known in the firearm art. For example, a simple hammer release assembly may comprise a hammer, or striking element, a catch on the surface of the hammer, a hammer spring and a trigger which operatively engages the hammer catch either directly or through a trigger rod. The hammer is typically rotatable about an axis by force of the hammer spring and is biased to travel through a strike path from a cocked position to a firing/rest position, at which point the hammer may strike a firing pin to discharge a round from the firearm. The hammer may be held in the cocked position by the engagement of the trigger with the hammer catch and may be released therefrom by an operator activating the trigger.
During operation, the hammer is rotated to a cocked position against the force of the hammer spring. When the hammer reaches the cocked position, the hammer catch engages the trigger or trigger rod and, under force of the hammer spring, the surface of the hammer catch and the trigger are pressed together perpendicular to the direction of motion of the hammer. The action of pressing the hammer and the trigger together creates a friction force which, along with a component of the hammer spring force, must be overcome to release the hammer and allow the hammer to rotate to the firing position. By varying the position of the hammer catch and trigger or trigger rod, the amount of friction which must be overcome to fire the weapon can be similarly varied. By varying the amount of force necessary to discharge the firearm, differing trigger resistances can be realized.
A marksman who wishes to discharge the firearm must overcome a number of firing forces to complete the operation. Specifically, the marksman must overcome the release force which comprises the friction force between the hammer catch and trigger, the spring force which holds the trigger in the rest position, as well as the friction force which opposes the movement of the trigger, and in some cases, the friction local to the trigger rod.
Firearms may be used in many different situations, for example military, police, recreation, or competition. In the situation where the firearm is a high capacity sport weapon, the firing forces discussed above, should be minimized, since a weapon in this class is only loaded at a shooting range immediately before firing, and is loaded by a skilled marksman with extreme care. On the other hand, when the firearm is a military class weapon, extreme caution must be used in reducing the firing forces since the weapon is subject to many unusual situations. For example a military weapon may be jostled or thrown to the ground, a marksman may be hindered by wearing thick, clumsy gloves, or the weapon may be subject to harsh environmental factors such as mud and rain. The harsh conditions associated with military use make it necessary to maximize the firing forces. If, for instance, a military weapon falls from an elevated position, it will strike the ground with an increasing velocity and at varying angles, releasing impact forces on the trigger and trigger rod. To prevent the weapon from firing, the firing forces must be greater than the impact forces imparted under these circumstances. Therefore, military and police weapons necessarily have harder trigger-pulls (the force necessary to activate the weapon) than do sports weapons. Similarly, normal firearm usage such as hunting, military shooting sports, self-protection and recreational use have trigger-pulls which lie between those of military and sport use because the weapons are generally well cared for and yet still subject to varying environmental conditions.
Ignoring, for the moment, the use of additional apparatuses designed to ease the force required to pull the trigger, i.e., to attain a xe2x80x9chair trigger,xe2x80x9d a typical firearm used for normal firearm usage requires approximately 15 to 20 Newtons of force to discharge. Forces in this range are comfortable and are considered xe2x80x9csoftxe2x80x9d for an experienced marksman. Military firearms, however, can require up to 50 Newtons of force to cause discharge, while sport pistols may require as little as 0.3 Newtons.
In order to produce a civilian version of a military weapon, the trigger-pull on the military version cannot be simply reduced, if the intent is to produce a civilian version suitable for multiple uses, for example, military reserves, sports and hobbies. The reason is, that the spring forces and the angle of the contact surfaces between the catch and the trigger (or the trigger-rod) cannot, due to safety restraints, be changed at will beyond certain limits.
One way to reduce the friction force is by polishing and buffing the seating and contact surfaces. This technique, however, is expensive, time consuming, and vulnerable to error. Furthermore, the polished trigger is extremely sensitive to any light contaminate, such as air borne sand particles, which could nullify any reduction of friction force achieved by such polishing.
Another method of reducing the friction force is by inserting intermediate linkages, transmission levers and the like, between the trigger and the hammer. This method, however, is very complicated and often difficult to implement due to space limitations, cost of manufacture and design, and the craftsmanship skill required.
A hammer release apparatus is disclosed for use in a firearm for reducing a pull resistance associated with discharging the weapon. The apparatus includes a pivotably mounted hammer having a stop notch, and a projection. Operably connected to the hammer is a hammer spring for generating a rotational force biasing the hammer from a cocked position toward a firing position. The hammer release apparatus includes a trigger having an engagement nose at one end and a spring for biasing the trigger to a rest position. The trigger is actuatable, against a force of the trigger spring from a rest position into a depressed position for discharging the firearm. A pivotably mounted trigger lever is located to engage the stop of the hammer, and to engage the trigger engagement nose. A pivotably mounted restraining apparatus having a catch disposed to restrainingly engage the projection of the hammer is biased by a spring to generate a force counter to the rotational force of the hammer spring.